A blog about my first hand use of the humble Philips compact cassette as a music recording and listening medium.

Sunday, November 29, 2015

Commonly Available Test Cassette Tapes, Anyone?

Even though Mobile Fidelity Sound Labs’ Geo Tape is the one
often mentioned, are there more widely available test cassette tapes out there?

By: Ringo Bones

Believe it or not, even well into the 1990s – and probably
even until this day – there’s still no agreed for the level at which the 0VU
peak record level is set on high fidelity cassette tape decks. During the
1990s, the 200nWb (nano Weber) Dolby flux was most commonly used for quality
budget decks, but lower down the price scale on budget designs with inferior
tape heads that would overload at a much lower level, 0VU is set -3dB below
Dolby. Some top line models, like Nakamichi, have their 0VU set high up at IEC
0dB flux of 250nWb which many audiophiles and engineers, then and now, think is
most sensible. But is there a reliable way to “calibrate” the cassette tape
decks you currently own regardless of quality even if you don’t have access to
a sophisticated signal generator and an oscilloscope?

The British made Harrison Test Cassette available from
Canford Audio which retailed for around £20 back in the mid 1990s is one of the
most widely available and often turns up in garage sales and weekend swap meets.
This has Dolby level plus other tests that are useful in aligning cassette tape
decks. While the “Cadillac” of test cassette tapes are those BASF IEC test
tapes, especially those that are IEC Primary Reference Standard which back in
the mid 1990s costs £69.20 each. But it is a very reliable way to establish IEC
0dB using the “Level Control 315Hz Code-XB” track and given that it is a
premium quality cassette test tape, it can establish IEC reference level to a
degree of certainty manufacturers cannot question.

After having reliably establish IEC 0dB, you can now record
to around +4dB above it on musical peaks on metal tape and around +2dB on
ferrics and chromes. And don’t forget to add 2dB to these figures if you set the
0dB of your cassette tape deck at 200nWb Dolby flux. But the most effective
test you can perform after aligning your cassette tape deck is on how effectively
it can record music tracks.